Latest ArticlesA novel asymmetric [4 + 2] cycloaddition of 2-methylidenetrimethylene carbonate with pyrrolidone-derived enones has been achieved to produce the functionalized tetrahydropyran-fused spirocyclic scaffolds via palladium-catalysis. An array of enantioenriched spiro-pyrrolidine-2,3-diones bearing adjacent quaternary and tertiary stereocenters are obtained in high yields with excellent enantioselectivities (up to 96% yield and 99% ee). The further transformation of the product has been accomplished for the construction of medical interesting β2,2-amino acids and β-lactams. Preliminary mechanistic research was well conducted.
Macrocycle confinement induced guest near-infrared (NIR) luminescence was research hotspot currently. Here in, we reported a cucurbit[7]uril (CB[7]) confined 3,7-bis((E)-2-(pyridin-4-yl)vinyl)-10-H-phenothiazine bridged bis(4-(4-bromophenyl)pyridine) (G), which not only boosted its NIR luminescence but also realized detection of HClO/ClO− in living cells and lysosome imaging. Fluorescence spectroscopy experiments were performed to calculate the detection ability of probe G to HClO/ClO− up to 147 nmol/L. As compared with G, supramolecular probe G⊂CB[7] formed after encapsulated by CB[7], the detection ability towards HClO/ClO− was improved to 24 nmol/L which was ascribe to the macrocycle CB[7] confinement increasing the fluorescence intensity to 103 folds. Accompanying the excitation wavelength changing, the fluorescence red-shifted to 820 nm when excited by 570 nm light, which was used to NIR lysosome imaging. Meanwhile, the supramolecular assembly G⊂CB[7] was also successfully used to highly sense to exogenous HClO/ClO− in RAW 264.7 cells and live animal.
Cr(Ⅵ), one of the most hazardous metal pollutants, poses significant threats to the environment and human health. Herein, a novel MoS2 composite (MoS2/PVP/PAM) modified by polyvinylpyrrolidone (PVP) and polyacrylamide (PAM) was synthesized to enhance the removal of Cr(Ⅵ). Characterization analysis including SEM, XRD, FTIR, and XPS indicated that PVP and PAM could increase the interlayer spacing and the dispersibility of MoS2, and introduce pyrrolic N and amino functional groups. The batch experiments showed that MoS2/PVP/PAM represented excellent Cr(Ⅵ) removal performance over a wide pH range, and exhibited a significantly higher maximum Cr(Ⅵ) adsorption capacity (274.73mg/g, at pH 3.0, and 298K) than pure MoS2. The adsorption of Cr(Ⅵ) followed Langmuir and pseudo-second-order kinetic model, which was a homogeneous monolayer chemisorption process. MoS2/PVP/PAM showed stable removal of Cr(Ⅵ) in the presence of humic acid (HA), interfering cations and anions at different concentrations. Moreover, it had excellent selectivity for Cr(Ⅵ) (Kd value of 1.69× 107mL/g) when coexisting with a variety of competing ions. Multiple characterization revealed that Cr(Ⅵ) was reduced to low toxicity Cr(Ⅲ) by Mo4+ and S2−, and then chelated on the surface of the adsorbent by pyrrolic N. This research expanded the design concept for MoS2 composites by demonstrating the potential of MoS2/PVP/PAM as a promising material for selective elimination of Cr(Ⅵ) in water.
The classification of π-/σ-aromaticity depends on the electrons with the dominating contributions. Traditionally, π- and σ-aromaticity are used to describe the unsaturated and saturated systems, respectively. Thus, it is rarely reported that π-aromaticity is dominated in a saturated system. Here we demonstrate that π-aromaticity could be dominating in several fully saturated four-membered rings (4MRs), supported by various aromaticity indices including ΔBL, NICS, EDDB, MCI, and AdNDP. The origin of such π-aromaticity in saturated rings could be attributed to an introduction of two additional electrons into the π-type LUMO of the parent neutral species. Our findings represent a novel approach to achieve π-aromaticity into a fully saturated system which has traditionally been dominated by σ-aromaticity.
Lateral flow immunoassay (LFIA) has become popular in laboratories, at-home testing, and medical diagnostics due to its minimal cost and user-friendliness. Nevertheless, conventional test strips based on colloidal gold can only obtain qualitative or semi-quantitative results with low sensitivity. In this work, Au-Fe3O4 dumbbell-like nanoparticles were synthesized and used as the LFIA labelling marker for highly sensitive colorimetric-photothermal dual-mode detection of SARS-CoV-2 spike(S) protein. The unique dumbbell structure of Au-Fe3O4 NPs makes it possible to combine the best features of both Au NPs and Fe3O4 NPs. The increased surface area of these NPs enhances their LSPR effect and photothermal effect, which achieves signal amplification to increase sensitivity. The Au-Fe3O4 NPs modified with S protein antibody could identify S protein in samples, which were recognized and accumulated on T-line by another antibody, generating color band for qualitative colorimetric detection. The T-line was irradiated by laser to obtain temperature change for quantitative detection of photothermal. In optimized conditions, the detection limit was 1.22 pg/mL, three orders of magnitude more sensitive than colorimetric detection. Finally, the approach was performed on SARS-CoV-2 pseudovirus samples and outperformed traditional colloidal gold strips. This LFIA platform exhibits significant promise for practical implementation, as it can satisfy the need for low-cost, high-sensitivity, and home-based quantitative detection for respiratory infectious diseases.
The over-exploitation of fossil fuel energy has brought about serious environmental problems. It would be of great significance to construct efficient energy conversion and storage system to maximize utilize renewable energy, which contributes to reducing environmental hazards. For the past few years, in terms of electrocatalysis and energy storage, carbon fiber materials show great advantages due to its outstanding electrical conductivity, good flexibility and mechanical property. As a simple and low-cost technique, electrospinning can be employed to prepare various nanofibers. It is noted that the functional fiber materials with different special structure and composition can be obtained for energy conversion and storage by combining electrospinning with other post-processing. In this paper, the structural design, controllable synthesis and multifunctional applications of electrospinning-derived functional carbon-based materials (EFCMs) is reviewed. Firstly, we briefly introduce the history, basic principle and typical equipment of electrospinning. Then we discuss the strategies for preparing EFCMs with different structures and composition in detail. In addition, we show recently the application of advanced EFCMs in energy conversion and storage, such as nitrogen species reduction reaction, CO2 reduction reaction, oxygen reduction reaction, water-splitting, supercapacitors and ion batteries. In the end, we propose some perspectives on the future development direction of EFCMs.
We report the unprecedent Pd(I) catalyzed ring-opening arylation of cyclopropyl-α-aminoamides. This protocol allows facile access to biologically important α-ketoamide-containing oligopeptides and even more challenging peptide-natural product conjugates. Site selectivity was achieved by introduction of special unnatural amino acids, which also meets the requisite of bioorthogonal chemistry. Mechanism investigations reveals a distinct domino radical ring-opening process through Pd(I) catalysis.
The hydrosilylation of unsaturated carbon-carbon bonds is one of the most critical reactions in silicone industrial production. The homogeneous Speier's catalyst, Karstedt's catalyst, and other noble metal-based catalysts are widely used. However, simplifying the separation of the homogeneous catalyst from reaction products and reducing the high cost of precious metals is still challenging. This review describes the recent development of heterogeneous catalysts for alkene, alkyne, and allene hydrosilylations, which can effectively solve problems in homogeneous hydrosilylation.
Copper phthalocyanine (CuPc) is adopted as an electrolyte additive to stabilize lithium anode for lithium-sulfur (Li-S) batteries. CuPc with a planar molecular structure and lithiophilic N-containing group, is likely to be adsorbed on the surface of Li anode to form a coating layer, which can restrict the direct contact between Li anode and solvents, and guide the uniform deposition of Li+ ions. The Li||Li symmetric cells demonstrate a stable cycle performance, and Li||Cu cells show high Coulombic efficiencies. In Li-S batteries, the formed stable solid-electrolyte interface (SEI) film containing copper sulfides can protect Li anode from the polysulfide corrosion and side reactions with the electrolyte, leading to the compact and smooth surface morphology of Li anode. Therefore, the Li-S batteries with CuPc additive deliver much higher capacity, better cycle performance and rate capability as compared to the one without CuPc additive.
Dendritic cell (DC)-targeted delivery of mRNA is a prominent method to boost the efficacy of mRNA tumor vaccines. The targeting ligands are often modified on nanocarriers by polyethylene glycol (PEG) linker in mRNA delivery systems. Whether the PEG linker length influences the targeting delivery efficiency of mRNA nanocarrier in vivo remains unclear. Here, we designed and constructed DC-targeted mRNA delivery systems modified by mannose via different PEG linker lengths (100/400/1000/2000) (MPn-LPX). The top candidate MP400-LPX (the linker was PEG400) showed the optimal mRNA expression and antigen presentation owing to the highly efficient uptake by DCs. Furthermore, MP400-LPX could better inhibited tumor growth and extended survival in the E.G7-OVA lymphoma and TC-1 cervical tumor mouse model. Collectively, these results demonstrated that PEG400 was the optimal linker for the PEGylated DC-targeted mRNA vaccines. Our findings provided a new platform for the rational design of targeted mRNA nanovaccines with shorter-length PEG.
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